imprint:
American Society of Clinical Oncology (ASCO), 2022
Published in:Journal of Clinical Oncology
Language:
English
DOI:
10.1200/jco.2022.40.4_suppl.160
ISSN:
0732-183X;
1527-7755
Origination:
Footnote:
Description:
<jats:p> 160 </jats:p><jats:p> Background: c-Ros oncogene 1, receptor tyrosine kinase ( ROS1) rearrangements have been reported in colorectal cancer (CRC), but little is known about the molecular and clinical features of ROS1-driven CRC and the response to ROS1-targeted treatment in CRC patients. Methods: We report disease course and treatment response of an index patient with chemotherapy-refractory right-sided metastatic CRC, harboring an activating ROS1 fusion ( GOPC-ROS1). Moreover, we examined 40,589 patients with CRC who underwent comprehensive genomic profiling as part of routine clinical care at Foundation Medicine (Cambridge, MA); all classes of alterations in at least 324 genes were assessed, including ROS1. Results: The index patient experienced a rapid and sustained partial response to molecularly targeted treatment with crizotinib. After 15 months on crizotinib, disseminated tumor progression occurred, with KRAS Q61H emerging in tumor tissue (53.7% variant allele frequency (VAF)) and liquid biopsy (13.5% VAF). Within the clinical cohort, ROS1 genomic rearrangements ( ROS1 RE (+)) were identified in 34 out of 40,589 (0.08%) CRC samples. GOPC-ROS1 was the most commonly identified ROS1 fusion (11/34 samples), followed by TTC28-ROS1 (3/34 samples). All ROS1-alterations were found in microsatellite-stable (MSS) CRCs, and ROS1 genomic alterations were significantly enriched in KRAS wild type tumors ( KRAS mutations in 23.5% of ROS1 RE(+) vs. 49.8% of ROS1 RE(-), p=0.003). Conclusions: ROS1 rearrangements represent rare but clinically actionable molecular driver alterations in MSS CRCs. The detection of ROS1 fusion oncogenes in CRC can pose diagnostic challenges since intrachromosomal ROS1 fusions including GOPC-ROS1 and non-canonical ROS1 fusions such as TTC28-ROS1 can remain negative on fluorescence in situ hybridization and immunohistochemistry assays, respectively. NGS-based comprehensive molecular profiling may be a useful tool to screen for rare fusion oncogenes. </jats:p>